Using implants to lower anneal temperatures

ABSTRACT

A method for lowering the anneal temperature required to form a multi-component material, such as refractory metal silicide. A shallow layer of titanium is implanted in the bottom of the contact area after the contact area is defined. Titanium is then deposited over the contact area and annealed, forming titanium silicide. A second embodiment comprises depositing titanium over a defined contact area. Silicon is then implanted in the deposited titanium layer and annealed, forming titanium silicide. A third embodiment comprises combining the methods of the first and second embodiments. In further embodiment, nitrogen, cobalt, cesium, hydrogen, fluorine, and deuterium are also implanted at selected times.

This application is a division of U.S. Ser. No. 08/676,587 filed Jul. 8,1996, now U.S. Pat. No. 5,885,896.

FIELD OF THE INVENTION

The present invention relates to methods for forming semiconductordevice interconnects and, in particular, to a method for formingrefractory metal silicide at a metal/semiconductor interface.

BACKGROUND OF THE INVENTION

Contacts between metal and semiconductor active areas are currentlyimproved by forming a refractory metal silicide at the interface betweenthe two materials. Titanium silicide is the most commonly used silicide.Titanium is deposited or sputtered on the semiconductor active area andannealed to form titanium silicide. This provides a good, low resistancecontact.

Borophosphosilicate glass (BPSG) is used as a device insulator,surrounding contact areas. Recently, in order to get BPSG to reflow atlower temperatures, the amount of dopants in the BPSG film is beingincreased. It is desirable to lower the reflow temperature of BPSG toavoid diffusion of dopants into undesired areas during high temperaturesteps. Normally, reflow temperatures exceed those required duringannealing process steps. However, the addition of dopants causes BPSG toreflow even at the temperatures required for the titanium annealprocess. This is undesirable because it causes titanium to buckle,resulting in degradation of contacts by increasing their resistance.This is counterproductive to the main reason for forming titaniumsilicide at semiconductor/metal interfaces--to improve contacts bylowering their resistance.

The addition of a refractory metal nitride layer at the surface of therefractory metal silicide provides both a barrier to diffusion into thecontact, and helps with the adhesion of the refractory metal silicide tothe metal, which may comprise tungsten, aluminum, and similar conductivemetals. Conventionally, such layers are formed by annealing in anitrogen-containing ambient simultaneously with forming refractory metalsilicide because it is important that a barrier nitride layer formsimultaneously with titanium silicide, so that both can be formed in oneprocessing step. Typically, titanium silicide is used for the refractorymetal silicide and titanium nitride is used for the barrier layer.

As devices are becoming smaller, there is a need for lowering thetemperature at which the refractory metal anneal occurs when formingrefractory metal silicide at semiconductor/metal interfaces. In smallerdevices, the acceptable amount of thermal-induced dopant diffusion islower. There is a further need for lowering the temperature at whichrefractory metal nitride is formed in order that the refractory metalnitride layer can be formed simultaneously with the refractory metalsilicide layer. It is paramount that the temperature of these anneals belowered so that low temperature reflow doped oxide insulator layers canbe used.

SUMMARY OF THE INVENTION

A method for lowering the anneal temperature required to form amulti-component material, such as refractory metal silicide, isdescribed. The method is described with reference to the most commonrefractory metal silicide, titanium silicide, and a typical insulatormaterial such as borophosphosilicate glass (BPSG) or other suitableinsulative material. Insulator materials are deposited prior todepositing refractory metals and subsequently annealing to formsilicide. Lowering the anneal temperature prevents the BPSG insulatorfilm from reflowing at undesired times, which, if not prevented, causestitanium buckling. The invention is applicable to other semiconductorstructures, which do not comprise BPSG as an insulator film, such asthose using a doped oxide insulating film. One advantage of theinvention is that lower processing temperatures prevent unwanted dopantdiffusion at higher temperatures, which is a limiting factor in themanufacture of small devices.

In one embodiment of the invention, a shallow layer of a refractorymetal, such as titanium, is implanted in the bottom of a defined contactarea, such as a contact hole defined over a silicon substrate. Therefractory metal is then deposited over the contact area and annealed,forming a refractory metal silicide in the area where the refractorymetal is implanted. Due to the increased concentration of refractorymetal in the contact area, annealing is performed at lower temperaturesdue to the decreased diffusion lengths of silicon/refractory metalrequired to form the contact.

In a second embodiment of the invention, after a contact area isdefined, a refractory metal is deposited over the contact area. Siliconis then implanted in the deposited refractory metal layer. Annealingcauses refractory metal silicide to form in the region where therefractory metal is deposited, in contact with the underlying siliconsubstrate.

In a third embodiment of the invention, the previous two embodiments arecombined. A shallow layer of a refractory metal, such as titanium, isimplanted in the bottom of a defined contact area, such as a contacthole defined over a silicon substrate. The refractory metal is thendeposited over the contact area. Silicon is then implanted in thedeposited refractory metal layer. Annealing causes refractory metalsilicide to form in the region where the refractory metal is depositedand implanted, in contact with the underlying silicon substrate.

In a further embodiment of the invention, an additional step comprisesimplanting nitrogen over the deposited refractory metal layer prior tothe anneal step. Refractory metal nitride is then formed simultaneouslywith refractory metal silicide during the anneal step. In yet a furtherembodiment, nitrogen is implanted subsequent to annealing to form arefractory metal silicide. The nitrogen implant lowers the temperatureat which the refractory metal nitride is formed by decreasing thenitrogen/refractory metal diffusion lengths required to form the nitridelayer. Refractory metal nitride helps provide a barrier to unwanteddiffusion into the contact.

In yet a further embodiment of the invention, an additional stepcomprises implanting an element selected from the group consisting of:cobalt, cesium, hydrogen, fluorine, and deuterium in the bottom of thecontact area, prior to implanting a refractory metal. In still anotherembodiment, an element selected from the group consisting of: cobalt,cesium, hydrogen, fluorine, and deuterium is implanted in the depositedtitanium layer, prior to implanting silicon therein. In still anotherembodiment, an element selected from the group consisting of: cobalt,cesium, hydrogen, fluorine, and deuterium is implanted in the refractorymetal silicide layer subsequent to the anneal step and prior tosubsequent process steps. The addition of such an implant furtherdefines grain structure and lowers the temperature needed to form therefractory metal silicide layer when it is performed prior to the annealstep, which forms the silicide.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional representation illustrating a typicalsemiconductor interconnect.

FIGS. 2a,b,c,d are cross-sectional representations illustrating oneembodiment of the present invention, where a refractory metal isimplanted in the contact area before refractory metal deposition, toform refractory metal silicide.

FIGS. 3a,b,c,d are cross-sectional representations illustrating anotherembodiment of the present invention, where silicon is implanted in thecontact area after refractory metal deposition, to form refractory metalsilicide.

FIGS. 4a,b,c,d,e are cross-sectional representations illustratinganother embodiment of the present invention, where a refractory metal isimplanted in the contact area before refractory metal deposition, andwhere silicon is implanted in the contact area after refractory metaldeposition, to form refractory metal silicide.

FIGS. 5a,b,c are cross-sectional representations illustrating anotherembodiment of the present invention, where nitrogen is implanted in thedeposited refractory metal, to form refractory metal nitride.

DESCRIPTION OF THE EMBODIMENTS

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that other embodiments may be utilized and thatstructural, logical and electrical changes may be made without departingfrom the spirit and scope of the present invention. The followingdetailed description is, therefore, not to be taken in a limiting sense,and the scope of the present invention is defined by the appendedclaims. Numbering in the Figures is usually done with the hundreds andthousands digits corresponding to the figure number, with the exceptionthat the same components may appear in multiple figures.

A method for lowering the anneal temperature required to form amulti-component material, such as refractory metal silicide, isdescribed. The method is described with reference to the most commonrefractory metal silicide, titanium silicide, and a typical insulatormaterial such as borophosphosilicate glass (BPSG) or other suitableinsulative material. Insulator materials are deposited prior todepositing refractory metals and subsequently annealing to formsilicide. Lowering the anneal temperature prevents the BPSG insulatorfilm from reflowing at undesired times, which, if not prevented, causestitanium buckling. The invention is applicable to other semiconductorstructures, which do not comprise BPSG as an insulator film, such asthose using a doped oxide insulating film. One advantage of theinvention is that lower processing temperatures prevent unwanted dopantdiffusion at higher temperatures, which is a limiting factor in themanufacture of small devices. In this invention, the refractory metalused to form the silicide can be any refractory metal, such as titanium,tungsten, tantalum, cobalt, and molybdenum.

As shown in FIG. 1, refractory metal silicide 108 is formed inaccordance with the method of the invention to decrease the ohmicresistance of a contact hole interconnect. A contact hole is defined bya silicon substrate 110, on the bottom, and an insulator material, 112,on the sides. The dimensions of the hole are not critical to thepractice of the invention. In fact, the invention can be applied toplanar surfaces as well as recesses in a semiconductor substrate. Priorto depositing metal 114 in the contact hole, respective layers ofrefractory metal silicide 116 and refractory metal nitride 118 areformed in the contact hole. Subsequently, metal 114, such as tungsten oraluminum, is deposited in the contact hole to form a low resistanceinterconnect.

In one embodiment of the invention, titanium silicide is formed in acontact hole by implanting titanium and annealing, as shown in FIGS.2a-2d. As shown in FIG. 2a, a contact hole 220 is defined, usingconventional techniques. The dimensions of the hole are not critical tothe invention. The contact hole 220 is defined by a silicon substrate222 on the bottom and BPSG sidewalls 224. The silicon substrate iscomprised of single crystal silicon, in order that the implant energyand anneal temperatures need not be as high, as implanted ions caneasily diffuse through such a crystalline structure. However, the scopeof the invention is not limited to single crystal silicon substrates.

Next, a shallow layer of titanium is implanted into the bottom of thecontact area, as shown in FIG. 2b, to form an implanted region 226. Thedepth of the implanted region 226 is between approximately 20 to 300angstroms. The depth of the implanted region 226 is dependent on manyparameters, such as: the desired thickness of the multi-componentmaterial formed, the type of implant ion, the target material, theimplant energy, and whether the target material is oriented such thatchanneling occurs. All of these parameters are easily selectable by oneof average skill in the art.

A titanium layer 228 is then deposited or sputtered over the contactarea, as shown in FIG. 2c. The depth of the titanium layer 228 isbetween approximately 150 to 1,500 angstroms. The depth of the titaniumlayer 228 is dependent on the desired thickness of the multi-componentmaterial formed, and the depth of the implanted region 226.

Subsequently, the structure is annealed for at least approximately 5seconds, forming titanium silicide 230 in the area where the titanium isimplanted, as shown in FIG. 2d. The thickness of the titanium silicidelayer 230 formed is between approximately 20 to 800 angstroms. Theannealing temperature depends on many parameters, including the amountand depth of ions implanted into the silicon substrate, the amount ofimplant damage to the substrate, the desired thickness of themulti-component material formed, and the type of implant ion. In theformation of titanium silicide, due to the increased concentration oftitanium in the contact area, annealing can be performed at lowertemperatures, such as between 500 to 950 degrees Celsius, because thediffusion lengths of silicon/titanium are decreased (i.e., eachconstituent in the multi-component compound does not have to travel asfar to react with the other component).

In a further embodiment, an additional step comprises implanting anelement selected from the group consisting of: cobalt, cesium, hydrogen,fluorine, and deuterium in the bottom of the contact area, prior toimplanting the refractory metal in the semiconductor substrate. In yetanother embodiment, an element selected from the group consisting of:cobalt, cesium, hydrogen, fluorine, and deuterium is implanted in therefractory metal silicide layer subsequent to the anneal step and priorto subsequent definition steps. The concentration of the additionalimplanted element depends on the aspect ratio (ratio of height todiameter) of the hole, among other parameters. As the aspect ratio of ahole increases, the concentration of dopants required increases. Theaddition of such an implant further defines grain structure and lowersthe temperature needed to form the refractory metal silicide layer whenperformed prior to the anneal step, which forms the silicide.

In a second embodiment of the invention, titanium silicide is formed ina contact hole 332 by implanting silicon in a titanium layer 338 andannealing, as shown in FIGS. 3a-3d. As shown in FIG. 3a, a contact hole332 is defined, using conventional techniques. The dimensions of thehole 332 are not critical to the invention. The contact hole 332 isdefined by a silicon substrate 334 on the bottom and BPSG sidewalls 336.The silicon substrate is comprised of single crystal silicon, in orderthat the implant energy and anneal temperatures need not be as high, asimplanted ions can easily diffuse through such a crystalline structure.However, the scope of the invention is not limited to single crystalsilicon substrates.

A titanium layer 338 is deposited or sputtered over the contact area, asshown in FIG. 3b, to a depth of between approximately 150 to 1,500angstroms. The depth of the layer 338 is dependent on the desiredthickness of the multi-component material formed. Next, silicon isimplanted into the titanium layer at the bottom of the contact hole, toform a silicon-rich region 340, as shown in FIG. 3c, throughout the areaof the deposited titanium layer. The depth of the implanted region 340is dependent on many parameters, such as the desired thickness of themulti-component material formed, the type of implant ion, the targetmaterial, and the implant energy. All of these parameters are easilyselectable by one of ordinary skill in the art.

Subsequently, the structure is annealed for at least approximately 5seconds, forming titanium silicide 342 at the silicon/titaniuminterface, as shown in FIG. 3d, having a thickness of betweenapproximately 20 to 1,500 angstroms. The anneal temperature is betweenapproximately 500 to 950 degrees Celsius. The anneal temperature dependson many parameters, including: the amount and depth of ions implantedinto the deposited material, the amount of implant damage to thedeposited material, the desired thickness of the multi-componentmaterial formed, and the type of implant ion. Due to the increasedconcentration of silicon in the titanium at the bottom of the contactarea, annealing can be performed at lower temperatures because thediffusion lengths of silicon/titanium are decreased (i.e., eachconstituent in the multi-component compound does not have to travel asfar to react with the other component).

In a further embodiment, an element selected from the group consistingof: cobalt, cesium, hydrogen, fluorine, and deuterium is implanted inthe deposited titanium layer, prior to implanting silicon therein. Inyet another embodiment, an element selected from the group consistingof: cobalt, cesium, hydrogen, fluorine, and deuterium is implanted inthe refractory metal silicide layer subsequent to the anneal step andprior to subsequent definition steps. The concentration of theadditional implanted element depends on the aspect ratio (ratio ofheight to diameter) of the hole, among other parameters. As the aspectratio of a hole increases, the concentration of dopants requiredincreases. The addition of such an implant further defines grainstructure and lowers the temperature needed to form the refractory metalsilicide layer when performed prior to the anneal step, which forms thesilicide.

In a third embodiment of the invention, the previous two embodiments arecombined. Titanium silicide is formed in a contact hole by implantingtitanium and annealing, as shown in FIGS. 4a-4e. As shown in FIG. 4a, acontact hole 420 is defined, using conventional techniques. Thedimensions of the hole are not critical to the invention. The contacthole 420 is defined by a silicon substrate 422 on the bottom and BPSGsidewalls 424. The silicon substrate is comprised of single crystalsilicon, in order that the implant energy and anneal temperatures neednot be as high, as implanted ions can easily diffuse through such acrystalline structure. However, the scope of the invention is notlimited to single crystal silicon substrates.

Next, a shallow layer of titanium is implanted into the bottom of thecontact area, as shown in FIG. 4b, to form an implanted region 426. Thedepth of the implanted region 426 is between approximately 20 to 300angstroms. The depth of the implanted region 426 is dependent on manyparameters, such as: the desired thickness of the multi-componentmaterial formed, the type of implant ion, the target material, theimplant energy, and whether the target material is oriented such thatchanneling occurs. All of these parameters are easily selectable by oneof average skill in the art.

A titanium layer 428 is then deposited or sputtered over the contactarea, as shown in FIG. 4c. The depth of the titanium layer 228 isbetween approximately 150 to 1,500 angstroms. The depth of the layer 228is dependent on the desired thickness of the multi-component materialformed, and the depth of the implanted region 226.

Next, silicon is implanted into the titanium layer at the bottom of thecontact hole, to form a silicon-rich region 440, as shown in FIG. 4d,throughout the area of the deposited titanium layer 428. The depth ofthe implanted region 440 is dependent on many parameters, such as thedesired thickness of the multi-component material formed, the type ofimplant ion, the target material, and the implant energy. All of theseparameters are easily selectable by one of ordinary skill in the art.

Subsequently, the structure is annealed for at least 5 seconds, formingtitanium silicide 430 in the areas where the titanium and silicon areimplanted, as shown in FIG. 4e. The thickness of the titanium silicidelayer 430 formed is between approximately 20 to 1,500 angstroms. Theannealing temperature depends on many parameters, including: the amountand depth of ions implanted into the silicon substrate, the amount ofimplant damage to the substrate, the desired thickness of themulti-component material formed, and the type of implant ion. In theformation of titanium silicide, due to the increased concentration oftitanium in the contact area, annealing can be performed at lowertemperatures, such as between 500 to 950 degrees Celsius, because thediffusion lengths of silicon/titanium are decreased (i.e., eachconstituent in the multi-component compound does not have to travel asfar to react with the other component).

In a further embodiment, an additional step comprises implanting anelement selected from the group consisting of: cobalt, cesium, hydrogen,fluorine, and deuterium in the bottom of the contact area, prior toimplanting the refractory metal in the semiconductor substrate. In yet afurther embodiment, an element selected from the group consisting of:cobalt, cesium, hydrogen, fluorine, and deuterium is implanted in thedeposited titanium layer, prior to implanting silicon therein. In yetanother embodiment, an element selected from the group consisting of:cobalt, cesium, hydrogen, fluorine, and deuterium is implanted in therefractory metal silicide layer subsequent to the anneal step and priorto subsequent definition steps. The concentration of the additionalimplanted element depends on the aspect ratio (ratio of height todiameter) of the hole, among other parameters. As the aspect ratio of ahole increases, the concentration of dopants required increases. Theaddition of such an implant further defines grain structure and lowersthe temperature needed to form the refractory metal silicide layer whenperformed prior to the anneal step, which forms the silicide.

In a further embodiment of the invention, a titanium nitride layer isformed on the deposited titanium layer, as shown in FIGS. 5a-5c,simultaneously with formation of the titanium silicide layer. Forexample, after titanium is implanted in a silicon substrate 544 at thebottom of a contact hole 548 having sides of insulating material 546 toform implanted region 526, a layer of titanium 550, having a thicknessof between approximately 150 to 1,500 angstroms, is then deposited overthe structure, as shown in FIG. 5a. The depth of the layer 550 isdependent on the desired thickness of the multi-component materialformed. Silicon is then implanted in the deposited titanium layer 550,to form a silicon-rich region 540 and nitrogen is implanted into thedeposited titanium layer 550 prior to the anneal step, to formnitrogen-rich regions 552, as shown in FIG. 5b. The depth of theimplanted region 552 is approximately between 20 to 300 angstroms. Thedepth of the implanted region 552 is dependent on many parameters, suchas: the desired thickness of the nitride layer formed and the implantenergy. All of these parameters are easily selectable by one of averageskill in the art.

Titanium nitride 554 is then formed during the anneal step,simultaneously with formation of 530, as shown in FIG. 5c. The annealtemperature ranges from between approximately 500 to 950 degreesCelsius. The nitrogen implant provides a reduction in the temperature atwhich the titanium nitride is formed by decreasing the nitrogen/titaniumdiffusion lengths (i.e., each constituent in the multi-componentcompound does not have to travel as far to react with the othercomponent). It is critical to employ this aspect of the invention whenforming titanium silicide in accordance with one of the embodiments ofthe invention because the temperature is lowered during the annealingstep. Using conventional techniques to form a nitride layer 554, byannealing in a nitrogen ambient alone, does not provide a nitride layer554 of the desired thickness at decreased processing temperatures. Thisaspect of the invention is applicable to other embodiments of theinvention as well.

When forming a titanium nitride layer in accordance with this furtherembodiment of the invention, annealing in a nitrogen ambient is notrequired. However, annealing in a nitrogen ambient in combination withthis aspect of the invention further increases the rate of formation oftitanium nitride for a given temperature. Furthermore, this allowsformation of titanium nitride 118 on the sidewalls of a contact wallalso, as shown in FIG. 1, rather than only in selectively-implantedareas, as illustrated in FIGS. 5a-5c. However, nitrogen can also beimplanted at an angle, so that the sidewalls of a contact hole formtitanium nitride 118 during subsequent anneal steps, without thenecessity of annealing in a nitrogen ambient. The angle of implant isadjusted, as well known to one skilled in the art, to achieve thedesired depth of implant on the contact hole sidewalls. Adjusting theangle between approximately 0 and 50 degrees provides this variabilityin implant depth. It is preferable, however, to have an implant angle ofapproximately 27 degrees for a typical contact hole.

In yet a further embodiment, a titanium nitride layer is formed afterformation of the titanium silicide layer. The same process steps asdescribed previously are followed. The anneal step will notsimultaneously form titanium silicide, however.

It is to be understood that the above description is intended to beillustrative, and not restrictive. Many other embodiments will beapparent to those of skill in the art upon reviewing the abovedescription. The scope of the invention should, therefore, be determinedwith reference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

What is claimed is:
 1. A method for forming refractory metal silicide,comprising:forming a layer of refractory metal on a substrate;implanting silicon into the layer of refractory metal, to form animplanted region; annealing to form refractory metal silicide,comprising at least the refractory metal and silicon; and implanting anelement selected from the group consisting of cobalt, cesium, anddeuterium into the layer of refractory metal.
 2. The method of claim 1,wherein the refractory metal is selected from the group consisting oftitanium, tungsten, tantalum, cobalt and molybdenum.
 3. The method ofclaim 1, wherein the layer of refractory metal is at least 150 angstromsthick and the implanted region is approximately as thick as the layer ofrefractory metal.
 4. The method of claim 1, wherein annealing to formrefractory metal silicide comprises annealing at a temperature ofbetween approximately 500 to 950 degrees Celsius for at leastapproximately 5 seconds.
 5. The method of claim 1, wherein implanting anelement selected from the group consisting of cobalt, cesium, anddeuterium into the layer of refractory metal occurs at a time selectedfrom the group consisting of the times of prior to implanting thesilicon and subsequent to annealing.
 6. The method of claim 1, andfurther comprising implanting nitrogen into the implanted region at atime selected from the group consisting of prior to annealing andsubsequent to annealing, thereby forming implanted nitrogen, wherein thedepth of the implanted nitrogen is approximately between 20 to 300angstroms.
 7. A method for forming a plurality of compounds on asemiconductor substrate, comprising:forming a layer of material,comprising a first element, on the substrate; implanting a secondelement into the layer of material, to form a first implanted region;implanting a third element into the layer of material, to form a secondimplanted region; annealing to form at least two compounds, the firstcompound comprising at least the first and second elements, and thesecond compound comprising at least the first and third elements; andimplanting an element selected from the group consisting of cobaltcesium, and deuterium at a time selected from the group consisting ofthe times of prior to implanting the second element, prior to implantingthe third element, and subsequent to annealing.
 8. The method of claim7, wherein forming a layer of material comprising a first elementcomprises a refractory metal selected from the group consisting oftitanium, tungsten, tantalum and molybdenum.
 9. The method of claim 7,wherein implanting a second element comprises implanting silicon. 10.The method of claim 7, wherein implanting a third element comprisesimplanting nitrogen.
 11. The method of claim 7, wherein annealingcomprises annealing in a nitrogen-containing ambient.
 12. The method ofclaim 7, wherein annealing comprises annealing at a temperature ofbetween approximately 500 to 950 degrees Celsius.
 13. A method forforming titanium silicide on a silicon substrate, comprising:forming atitanium layer on the substrate; implanting silicon into the titaniumlayer to form an implanted region; annealing to form titanium silicide;and implanting an element selected from the group consisting of cobalt,cesium, and deuterium into the titanium layer at a time selected fromthe group consisting of the times of prior to implanting the silicon andsubsequent to annealing.
 14. The method of claim 13, wherein forming atitanium layer on the substrate comprises forming a titanium layer on abottom of a contact hole.
 15. The method of claim 14, wherein forming atitanium layer on a bottom of a contact hole comprises a contact holefurther having sides, wherein the sides of the contact hole are definedby an insulator material selected from the group consisting ofborophosphosilicate glass and doped oxides.
 16. The method of claim 13,further comprising implanting nitrogen into the titanium layer at a timeselected from the group consisting of the times of prior to annealingand subsequent to annealing, wherein the depth of the implanted nitrogenis approximately between 20 to 300 angstroms.
 17. The method of claim16, wherein forming a titanium layer on the substrate comprises forminga titanium layer on a bottom of a contact hole, further wherein thecontact hole has sides defined by an insulator material selected fromthe group consisting of borophosphosilicate glass and doped oxides,still further wherein the nitrogen is implanted at an angle of betweenapproximately 0 and 50 degrees from a plane perpendicular to the bottomof the contact hole.
 18. The method of claim 17, wherein implantingnitrogen comprises implanting nitrogen at an angle of approximately 27degrees from a plane perpendicular to the bottom of the contact hole.19. A method for forming a refractory metal silicide, comprising:forminga layer of refractory metal on a substrate, wherein the refractory metalis selected from the group consisting of titanium, tungsten, tantalum,cobalt and molybdenum; implanting silicon into the layer of refractorymetal; annealing to form refractory metal silicide; and implanting anelement selected from the group consisting of cobalt, cesium, anddeuterium into the layer of refractory metal.
 20. A method for formingrefractory metal silicide, comprising:forming a layer of refractorymetal on a substrate, wherein the refractory metal is selected from thegroup consisting of titanium, tungsten, tantalum, cobalt and molybdenum;implanting silicon into the layer of refractory metal; annealing to formrefractory metal silicide; and implanting an element selected from thegroup consisting of cobalt, cesium, and deuterium into the layer ofrefractory metal at a time selected from the group consisting of thetimes of prior to implanting silicon and subsequent to annealing.
 21. Amethod for forming refractory metal silicide, comprising:forming a layerof refractory metal on a substrate, wherein the refractory metal isselected from the group consisting of titanium, tungsten, tantalum,cobalt and molybdenum; implanting silicon into the layer of refractorymetal, to form an implanted region; annealing to form refractory metalsilicide, comprising at least the refractory metal and silicon;implanting nitrogen into the implanted region at a time selected fromthe group consisting of prior to annealing and subsequent to annealing;and implanting an element selected from the group consisting of cobalt,cesium, and deuterium into the layer of refractory metal at a timeselected from the group consisting of the times of prior to implantingthe silicon and subsequent to annealing.
 22. A method for forming aplurality of compounds on a semiconductor substrate, comprising:forminga layer of metal, comprising a first element, on the substrate;implanting a second element into the layer of metal, to form a firstimplanted region; implanting a third element into the layer of metal, toform a second implanted region; annealing to form at least twocompounds, the first compound comprising at least the first and secondelements, and the second compound comprising at least the first andthird elements; and implanting an element selected from the groupconsisting of cobalt cesium, and deuterium at a time selected from thegroup consisting of the times of prior to implanting the second element,prior to implanting the third element, and subsequent to annealing.